小粉虫各发育期的临界热极值和失水的研究

本文研究了升高环境温度对小粉虫(Alphitobiusdiaperinus,鞘翅目拟步行虫总科)末龄幼虫、蛹以及成虫的失水和热敏性(临界热极值,Criticalthermalmaximum,CTmax)的影响。小粉虫成虫和蛹的CTmax值显著低于末龄幼虫(末龄幼虫:CTmax=48.5±0.5℃;蛹:CTmax=48.0±0.9℃;成虫:CTmax=47.8±1.1℃)。此外,成虫的适应性对其CTmax没有显著的影响。在20至60℃连续记录失水值中,三个龄期之间存在显著差异。随着超过临界点温度(约为40℃)的快速升高,末龄幼虫与成虫的失水程度相近。蛹具有明显低的失水速率,即使在温度高于40℃的情况下。当温度升高10℃时(25-35℃),会造成小粉虫蛹和成虫失水增加2.0倍和2.6倍,分别为:Q10=2.05±0.70和2.49±1.31,而幼虫则为3.52±1.27。当高于35-45℃时,幼虫和成虫失水增加甚快(Q10=6.85±1.90和8.51±2.32)。而蛹在高于35-45℃时失水也增加(Q10=3.76±1.83),但低于幼虫和成虫。小粉虫的蛹处于静止和不取食状态,代谢速率较低,其具有特殊结构的气孔能较好地保持关闭状态,且蛹的表皮由脂肪和蛋白质组成,以上诸因素可解释其失水减少的原因

Critical thermal maximum and water loss in developmental stages of the lesser mealworm Alphitobius diaperinus

Effect of increasing ambient temperature on water loss and thermosensibility (critical thermal maximum,CTmax) was examined in last instar larvae, pupae and adults of Alphitobius diaperinus (Coleoptera: Tenebrionidae).CTmax was significantly lower in adults and pupae than in last instar larvae (last instar larvae: CTmax = 48.5 ± 0. 5℃ ,pupae: CTmax= 48.0±0.9℃ , adult: CTmax=47.8±1.1℃ ). Moreover, acclimation had no significant impact on adult CTmax. Water loss was recorded continuously between 20 and 60℃ and differed significantly among the three developmental stages. Last instar larvae and adults exhibited similar water losses with a sharp increase above a critical transition temperature (CTT), which is about 40℃. In pupae, a significantly lower rate of water loss was found, even above 40℃ . An increase of 10℃ (25 - 35℃ ) induced a 2.0 and 2.6-fold increase of the water loss in pupae and adults of A.diaperinus ( Q10 = 2.05±0.70 and 2.49±1.31, respectively) vs. 3.52±1.27 in larvae. Water loss was strongly increased over the range 35 - 45℃ in larvae and adults (Q10=6.85±1.90 and 8.51 ± 2.32). In pupae, Q10 was also increased over the range 35 - 45℃ (Q10 =3.76±1.83), but less than in larvae and adults. In A .diaperinus pupae,characterized by motionless without feeding ability, lower metabolic rate, better ability to keep the spiracles closed more often thanks to a specific structure, and the cuticular composition (surface lipids and proteins) may explain the reduced water loss [ Acta Zoologica Sinica 52 (1): 79 - 86, 2006].